BIOC34H3 Lecture : Lecture 24 Notes.pdf
Document Summary
Lecture 24: nervous and hormonal regulation of digestion: gi tract nerve plexes. Gut motility and the secretion of certain substances are controlled by two nerve plexes. Innervating the sub-mucosa layer is the submucosal nerve plexis, and innervating the smooth muscle is the myenteric nerve plexis. The submucosal plexis influences secretory activity - this is why it is located closer to the intestinal lumen. The smooth muscle can contract and relax without any nervous or hormonal regulation - however, it is often influenced by these factors: sensory pathways and receptors. There are a host of different receptor types within the gut that can sense the various chemical stimuli that arise from the breakdown of foodstuffs. There are three general types of receptors in the gut: mechanoreceptors, which sense the distension or stretching of the gut as it fills with food; there are chemoreceptors that sense changes in ph, sugars, amino acids, and fatty acids.
